随机验证码生成

 1 public static void CreateValidateGraphic(string validateCode, HttpContext httpContext)
 2     {
 3         Bitmap img = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 20);
 4         Graphics g = Graphics.FromImage(img);
 5         try
 6         {
 7             Random random = new Random();
 8             g.Clear(Color.White);
 9 
10             //图片的干扰线
11             for (int i = 0; i < 25; i++)
12             {
13                 int x1 = random.Next(img.Width);
14                 int x2 = random.Next(img.Width);
15                 int y1 = random.Next(img.Height);
16                 int y2 = random.Next(img.Height);
17                 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
18             }
19             Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
20             System.Drawing.Drawing2D.LinearGradientBrush brush = new LinearGradientBrush(
21                 new Rectangle(0, 0, img.Width, img.Height), Color.Blue, Color.DarkRed, 1.2f, true);
22             g.DrawString(validateCode, font, brush, 3, 2);
23             //图片前景干扰点
24             for (int i = 0; i < 100; i++)
25             {
26                 int x = random.Next(img.Width);
27                 int y = random.Next(img.Height);
28                 img.SetPixel(x,y,Color.FromArgb(random.Next()));
29                 
30             }
31             //图片边框线
32             g.DrawRectangle(new Pen(Color.Silver),0,0,img.Width-1,img.Height-1 );
33             MemoryStream memoryStream=new MemoryStream();
34             img.Save(memoryStream,ImageFormat.Jpeg);
35             httpContext.Response.Clear();
36             httpContext.Response.ContentType = "image/jpeg";
37             httpContext.Response.BinaryWrite(memoryStream.ToArray());
38         }
39         catch (Exception)
40         {
41 
42             throw;
43         }
44     }